1. Field of the Invention
The invention relates to an article of footwear, such as a mountain boot, and such as a mountain boot adapted for mountain racing.
2. Description of Background and Relevant Information
For an article of footwear, or for a boot, of the aforementioned type, the upper must fulfill several functions, such as the following:                stability of the foot and of the ankle and protection against sprains, particularly on sloping or uneven terrain;        “impermeability” or protection of the boot from the exterior, particularly rain and snow, but also a mechanical protection of the foot against debris, sharp stones, or other exterior attacks;        foot comfort and, depending on the type of boot, thermal protection.        
Traditionally, boots of this type have an external upper that is made from very thick and strong leather, lined on the inside with comfort layers such as foam materials, and having an inner coating, such as leather.
Such boots are very heavy and have a minimum weight of about 2.8 kg per pair, or about 6.17 lbs per pair.
More recently, boots have been proposed whose outer upper is in fact a plastic shell, consequently particularly rigid and impermeable, and whose comfort is ensured on the inside by a removable liner.
Such boots are even heavier and have a minimum weight of about 3 kg per pair, or about 6.61 lbs per pair. Furthermore, their construction is very expensive as they require at least one pair of molds per boot size.
Even more recently, boots have been marked having a so-called mixed upper, i.e., one in which the outer upper is constituted of a strong fabric, such as the one known under the commercial name of CORDURA®, coated with a synthetic material.
Such boots tend to be lighter. However, their weight is still on the order of 2.6 kg per pair, or about 5.73 lbs per pair, and, furthermore, they are not suited for use in high mountains due to their lack of rigidity.